Method of forming metallic frame structures



Oct. 29, 1940. v LANG 2,219,595 METHOD OF FORMING METALLIC FRAME STRUCTURES Filed. Aug. 26, 1939 3 Sheets-Sheet 1 INVENTOR. ALBER'T LANG ATTORNEY Oct. 29, 1940. LANG 2,219,595

METHOD OF FORMING METALLIC FRAME STRUCTURES Filed Aug. 26, 1939 2 4a WT T 5 Sheets-Sheet 2 ELF-11 INVENTOR, ALBERT LANG ATTORNEY Oct. 29, 1940. LANG 2,219,595

I METHOD OF FORMING METALLIC FRAMESTRUCI'URES F iled Aug. 26, 1959 s Sheets-Sheet s r 1 4 H M g E517. F5551. F5525 Eli-1 5 H 22 4 222 ZI B 5G g 4 "Ki,

F1515. F 'I'EE.J. E's-7. FIE-.71.

INVENTOR. A L 8 ER T L A N6 ATTORNEY Patented Oct. 29, 1940 rarest orrlcs METHOD or FORMING METALLIC FRAME,

STRUCTURES Albert Lang, Berkeley, Calif. Application August 26, 1939, Serial No. 292,103

1 17 Claims.

is a continuation in part of Method of 3, 1938,

This application my pending application entitled forming metallic frames, filed January and bearing Serial No. 183,079.

The invention relates generally to the manufacture of metallic frame structures having angularly related portions and is more particularly directed to a method of forming a frame structure of this character from a single length or strip of rolled stock preformed to a desired crosssectional contour or from structural shapes of steel or other metals.

It is the principal object of the present invention to provide a new, improved and simpler -method of forming a frame structure having mitred and welded corners, in a manner which entirely eliminates the separate handling and mating of individual frame parts; which renders unnecessary the use of assembling 'templets, spacers, indexing'pins or like devices, and which enables frame structures of this nature to be manufactured with exceptional speed and econ omy. The method involves mitre cutting a single strip of material at points defining the locations of the respective corners of the completed frame, which mitre cuts do not completely sever the strip at such points but leave correlating ties at the intended corners which are bendable to permit said strip to be bent at said points to the desired frame form. The correlating ties are of sufficient strength to maintain the connected portions in correlated relationship during the bending operation. The welding of the mated edges at the corners of the frame is accomplished by bringing said edges to a welding temperature and the application thereto of a translating pressure of sufficient force to forge said edges into a substantially homogeneous weld. The invention. is exemplified in the following description and is illustrated by way of example in the accompanying drawings, in which:

Fig. l is a plan view illustrating one form of frame structure which may be constructed in accordance with the method of the present in-.

vention.

Fig. 2 is a semi diagrammatic view illustrative of certain steps in the method of manufacturing a frame structure of the general type shown in Fig. 1. V

Fig. 3 is an enlarged fragmentary view of the frame forming stock showing one of the mitre cuts formed therein.

Figs. 4 and 5 are detail views illustrating subsequent steps in the forming of a mitred frame corner from a strip mitre cut as shown in Fig. 3,

standard or special and the joining of the electric flash welding.

Fig. 6 is a View showing the frame corner of Figs. 4 and 5 in completed form.

Fig. '7 is a View, similar to Fig. 4, illustrating a 5 frame corner prepared for welding, by means of ordinary electric resistance butt welding.

Fig. 8 is a view showing the frame corner of Fig. '7 as completed ina manner to upset the connecting correlated tie.

Fig. 9 is a view, showing the frame corner of Fig. '7 as completed, after severing the tie.

Fig. 10 is a fragmentary View showing a screen frame forming strip mitre cut in accordance with the present invention.

Fig. llis-a fragmentary view showing the strip of Fig. 10' bent to form a frame corner.

Fig. 12 is a horizontal section through a door structure showing a metallic door frame of a type to which thepresent invention is applicable.

Fig. 13 is a fragmentary perspective view of a corner of the door frame of Fig. 12. V

Fig. 14 is a partial vertical section through a window structure showing a metallic window frame of a type to which the present invention is 5 applicable. I

Fig. 15 is a fragmentary perspective view of a corner of the window frame of'Fig..14.

Figs. 16 to 19 illustrate the forming of corner abutting edges thereof by structures from a strip mitre cut as shown in Fig. 16. i

Figs. 20 to 23 illustrate the forming of corner structures from a strip mitre cut as shown in Fig. 20.

Figs. 24 and 25 illustrate the forming of corner structures from a strip mitre cut as shown in Fig. 24. 1

Figs. 26 and 2? illustrate corner structures similar to those shown in Figs. 18 and 19 but of a lesser angle than ninety degrees.

Figs. 28 to 31 illustrate the forming of a corner a structure from a strip mitre cut as shownin Fig. 28.

In the art of forming frame structures having mitred and welded corners from preformed. metallic stock or from structural shapes of steel orother metals, it has heretofore been standard practice to out said stock into short lengths to correspond to the ends and sides of the frame and then weld these separate lengths at the cor- 0 ners along the diagonally cut edges. In such a method the operator must necessarily handle four separate pieces of stock in the construction of a rectangular frame and he must also properly position the adjacent parts with respect to each other before the welding operations are started. This entails the handling of at least two separate pieces at each weld and also requires time consuming effort to effect a neat and proper alignment of the parts.

To save time and eliminate'error in properly positioning such separate frame parts in cooperative aligned relationship, the standard practice has been to employ assembling templets, spacers, indexing pins or like devices, which expedients, while being of some advantage, have in no manner eliminated the necessity of the separate handling of detached frame parts.

In my improved method, the handling of separate pieces of the metal stock is entirely eliminated and the adjacent frame parts are connected in the proper order and in correlated relationship so that the frame structure may be constructed without the aid of assembling templets, spacers, indexing pins or like devices.

To accomplish my purpose, I form the frame structure from a single length or strip of metal stock in which I define the location of each frame corner by a mitre out which does not completely sever the strip but leaves a correlating tie that is of suflicient strength to maintain the adjacent frame partsconnected in correlated relationship and is, at the same time, bendable when subjected to a proper frame forming pressure.

When this mitre cut strip is bent to frame form to bring the opposed edges of the mitre cuts into welding relationship, I join these mating edges at each frame corner by heating the adjacent frame parts sufiicient to plasticise or bring said edges to a welding temperature and by subjecting said parts to a translating pressure of suflicient force to forge said edges into a substantially homogeneous weld.

To insure a uniform weld and to take full advantage of the productive speed of machine welding, I preferably accomplish the welding by means of what is known in the welding art as electric resistance welding in which a welding current is employed to plasticize the adjacent edges and a relatively high translating or upsetting pressure is applied to the adjacent parts to forge theseedges together.

In some instances it is preferable to apply the forging pressure before and during the application of the electric heating current so as to effect an upsetting of the correlating tie, while in other instances it will be preferable to utilize flash welding in which the opposed edges are lightly contacted during the initial heating so as to flash or burn away the tie before the forging pressure is applied. I may also elect to employ flash or other welding after the correlating tie is destroyed in other ways than by fusing. In either instance the actual welding is effected by abutting the plasticised edges under a translating pressure of sufiicient magnitude as to consolidate said edges into a substantially uniform weld of exceptional strength.

In Fig. l of the drawings is shown a rectangular frame such as may be formed in accordance with the improved method herein disclosed. Disregarding for the time being the dotted lines in this View, the frame comprises a single strip A of metal which has been mitre cut and bent to form adjacent frame portions a, b, c and d.

In the semi-diagrammatic view of Fig. 2 there is indicated mechanism by which certain steps of the method may be carried into effect although it will be understood that the method is not dependent upon such mechanism since it is evident that, particularly with small frame structures made of relatively light stock, the strip may be mitre cut with hand tools and manually bent to frame form without the employment of bending mechanism.

However, it is desirable, in all instances where production speed and accuracy is of importance, to employ such mechanisms as carrying into effect of the method of the present invention.

In Fig. 2 one of many possible arrangements is indicated as including a mitreing die I0 and a bending or angulating means I I which may be operated in timed relation with a suitable controlled feeding mechanism (not shown). Carrying out my improved method with mechanism of this general character, the strip A, with its lead end mitred as at e, will be fed in the direction of the arrow 1; and will be mitre cut by the mitreing die ID at properly spaced intervals to define the locations of the respective corners of the complete frame.

For the construction of a rectangular frame, each mitre cut B will be of substantially right angled form to extend approximately forty-five degrees on opposite sides of a plane perpendicular to the strip, and while each mitre cut B forms opposed edges I2 and I 3, which are aligned for subsequent abutting engagement, it is to be noted that these mitre out do not completely sever the strip A, but stop short of the outer edge of the strip so that at the apex of each mitre out B there is a correlating tie I 4 which connects the adjacent frame portions of the strip to maintain them in a predetermined correlated relationship.

When the strip A has advanced past the bending or angulating element II, as indicated in dotted lines in Fig. 2, and to bring its first mitre notch B to the bending station, the angulating element I l will be actuated to the position I la to bend the strip at the first tie I4 and angulate the frame section a in relation to the frame section b thus tosubstantially close said mitre cut and bring its opposed edges into mating relationship with the associated correlating tie I4 serving as a hinge for the angulating movement of the section a and serving to maintain the correlated relationship of these two connected frame sections. As each succeeding mitre cut B reaches the bending station, a similar bending operation takes place, and with the bending of the strip A at the third mitre cut B, the mitred end e of the strip will mate with the trailing end of the strip which will be similarly mitred, as shown in Fig. 1.

By thus bending the strip A at the connecting correlating ties I4, the frame is formed as an integral unit which may safely be handled as partially manufactured stock to be subsequently welded at the corners to complete the frame.

However, it is preferable to weld each corner as it is formed at the bending station, by applying to the adjacent angulated frame sections,

the welding current leads or electrodes I5 which' will be constructed and actuated to provide the necessary forging pressure, as will be understood by those skilled in the welding art, although in some cases it may be desired to simultaneously weld all of the corners after the frame is formed by the use of several sets of electrodes, as indicated in dotted lines in Fig. 1.

Figs. 3 to 6 of the drawings illustrate more clearly the method of forming and welding a frame corner, the strip A being formed from may expedite the 'necting web Z-bar stock and having an inner co-planar flange l6 and an outer co-planar flange H, which flanges extend in opposite directions from a conl8, as is indicated in Fig. 3. In this instance the mitre cut B is of approximate right angle form and'extends entirely through the inner flange i6 and the connecting web l3 and a substantial distance into the. outerflange II to leave at its apex only the bendable correlating tie M which connects the adjacent frame portions and maintains them correlated during the subsequent handling and bending operations.

In Fig. 4 the mitre cut strip A is shown bent to frame form, as previously described, and having applied to the adjacent frame'po'rtions the welding electrodes IS with their respective current leads l5a these being of the usual vise-jaw type and capable of relative translation towards each 4 other to provide the forging pressure necessary in resistance welding, as will be understood by those skilled in the art.

The welding of this frame corner may be effected by following the procedure incident to electric flash welding or that incident to what is usually termed resistance butt welding, although flash welding is in fact the same as resistance butt welding insofar as the actual welding is concerned, the diiference between the two being in the heating effect which prepares the opposed edges for the actual welding and the time of application of the required forging pressure.

Broadly, resistance welding comprises passing an electric current through abutting pieces of metal to plasticise the contacting edges'and applying thereto a clamping pressure of sufficient force to forge said edges into a consolidated substantially homogeneous weld, the term plasticise being herein employed to define the heating of said edges to a welding temperature which will render such edges plastic to a degree that will enable the applied pressure to forcesaid-edges beyond a mere meeting contact and actually upset and forge the edges together. Such forging pressure is necessary in order to prevent the forma- P tion of a porous and weak weld. The heat is developed between the surfaces in contact and de pends upon the current employed and the resistance of the contacting surfaces to the current flow, with such resistance varying inversely in relation to the clamping pressure which abuts the contacting surfaces of the work during the heating period. i

In flash welding, the pieces to be joined are brought into welding relationship with their surfaces lightly touching and the welding current is then applied while the pieces are slowly moved towards each other during the heatingperiod.

As the surfaces make contact, the metal is burned in a continuous flash of molten metal. This flashing prepares the surfaces for intimate contact and leaves them plastic for the upsetting and forging which is subsequently eifected by forcing the pieces together under a relatively high forging pressure.

The ordinary butt welding differs from the flash welding in that comparatively high forging pressure is applied before the current is applied and is maintained throughout the welding process. The pressure decreases the resistance and'thus. increases the time required to bring the contacting surfaces to a welding temperature. Also, by applying the higher pressure during the heating period, flashing and burning of the metal is prevented.

the welding current is applied In Fig. 4 the strip A is shown as bent to substantially close the mitre cut B in preparation for a flash welding operation. In this view, the 0pposed edges l2 and i3 are shown slightly separated, this being for the purpose of clearlyv indicating that in flash welding these edges are not subjected to a high clamping pressure, but are only lightly contacted or at least brought into such close relationship as to cause the welding current to are between said edges. With the application of the electric current, the tie l4 and the opposed edges will be fused and burned away in a continuous flash of molten metal, the opposed edges throughout the width of the strip being thus reduced to a molten or plastic state for forging.

In Fig. 5 such molten or plasticised edges are indicated at l2a and l3a.

pressure directed perpendicularly to said edges,

- as indicated bythearrows x, and of a magnitude In some instances it may be advantageous to sever or destroy the connecting tie l4 before the welding current is applied, by mechanical means, such as a saw 23, as indicated in Fig. 4. In such instances the flash welding will proceed in the usual manner and will produce a corner joint of r the same character as will be produced when the tie is destroyed by the flash welding-current.

In Fig. '7 the strip A is shown as bent to fully close the mitre out B in preparation. for an ordinary resistance butt welding operation in which the connected frame sections are forcefully clamped to bring the opposed mitred edges together under a relatively high pressure directed perpendicular to said edges, "as indicated by the arrows 2.

and continues throughout the entire welding operation. With the application of the welding current, the high pressure will effectively prevent arcing or flashing at the contacting surfaces and therefore will not destroy the connecting tie [4, but will merely heat it and the opposed mitred edges to a welding As this tie and said edges become plasticised, the high applied pressure will immediately become effective to translate the adj acent' frame sections with a force suflicient to upset said tie outwardly, as shown at flex in Fig. 8, and to forge the opposed plasticised edges together into a substantially homogeneous weld 2 I. a

The outwardly extending upset Mac tends to fill out or square the corner of the frame and may subsequently be dressed by suitable means to remove excess metal and true said corner.

As in the previously described flash welding operation, the tie 14 may be severed or destroyed by mechanical means before the ordinary butt welding operation and after said tie has performed the function of hingedly connecting the adjacent frame sections and maintaining them in correlated relationship during the handling and.bend-' ing operation. In this event the weld um produced by the ordinary butt welding operation will, in essential respects, be similar to-the weld !9 produced by the previously described flash welding operation, as is shown in Fig. 9.

- In Fig. 10 there is shown a portion of a screen frame forming strip Al which has a box-like outer portion 28 and an inwardly disposed upstanding and spaced flange 29, which, in conjunction with In the actual Welding' of these edges together, the opposed frame sectionsare subjected to a relatively high translating This high pressure is applied before channel 30.

the box-like portion 28, forms an intermediate In accordance with the present invention, a frame forming strip of this character will be provided with a mitre cut Bl at locations defining the respective corners of the frame. Such mitre cut will extend through the strip from its inside edge to a point corresponding to the inside surface of the outer side wall of the box-like portion 28 so as to leave at the apex of said mitre cut the correlating tie 14a which connects the adjacentframe sections and maintains them in correlated relationship, as previously explained in connection with the strip A. I

In forming a frame structure from the mitred strip Al, it will be bent at each tie Ma to close the respective mitre cut and dispose the adjacent frame sections in angled relationship, as shown in Fig. H. Each corner is then welded, as here- 'tofore explained, to complete the frame structiu'e.

In Fig. 12 ther type of be also formed in accordance with the present invention. The frame structure here shown is particularly adapted to the outlining of a door opening, and it therefore has a central raised portion 36 that will function as a door stop for a door 31, which may be mounted at either side of the frame. As here shown, a door 31 is mounted upon hinges 38, and at its free edge it is provided with the usual latch and door knobs 39.

As illustrated in Fig. 13 of the drawings, the door frame forming strip A2 has spaced flanges 40 that project outwardly and provide a means by which the door frame may be secured in a building structure. Strips of this type come from the rolling mill in relatively long straight lengths, from which the door frame may be formed by providing the mitre cuts 132 that extend through the strip to a point closely adjacent to the outer edges of the flanges 40 This will leave in each flange at the apex of each mitre cut a correlating tie l4b connecting the sides and end portions of the frame and having the same purpose and function as the previously de scribed correlating ties.

In Figs. 14 and 15 there is shown a further form of metallic frame, to which the present invention is also applicable. In this showing the metallic frame has outwardly extending it may be secured in. the window opening of a building. This frame has a central window guiding ridge 45, and at each side of this ridge there are cleat receiving grooves 46, into which cleats 41 may be placed to retain the upper and lower sashes 48 and 49 of a window in movable relation within the frame. This frame, like the frame shown in Figs. 12 and 13, is formed of rolled stock which comes in long strips, and when the frame forming strip A3 is provided with mitre cuts B3 at points corresponding to the corners of the window frame, in accordance with the present invention, the strip can then be bent at the correlating ties Me which are disposed at the apex of each of said mitre cuts. After the frame has been thus formed by bending the frame forming strip at the mitre cuts, each of the corners can then be welded, in the manner previously described, to complete the frame.

In Fig. 16 there is shown a portion of a strip A4 provided with a mitre cut B4 formed to provide a welding projection 22 laterally extended from one of the opposed mitred edges and a correlating tie I 4d connecting the adjacent frame of the drawings, there is shown ,a furmetallic frame structure, which may sections. In forming the frame structure from this character, said strip is bent at the connecting tie I 4:2 to angulate said sections and to contact the projection 22 with a comparable portion of the opposed mitred edge, as shown in Fig. 17. The welding of this corner structure may be accomplished byflash welding to produce a projection weld 23 at the inner corner and to destroy the tie Md and produce a weld 24 at the outer corner, as shown in Fig. 18. In event this corner structure is welded by the previously described ordinary resistance butt welding process, the tie l4d will be upset outwardly, as shown in Fig. 19.

If a strip A having a mitre cut B5 providing two welding projections 2211, as shown in Fig. 20, is employed, a bending of'the strip at the connecting correlating tie- He will contact both welding projections 22a with comparable portions of the opposed mitred edge, as shown in Fig. 21, and a subsequent flash welding operation will produce welds 23a and 2411, as shown in Fig. 22. In event the tie Me is destroyed by mechanical or other means after angulating the frame sections and before the welding operation, resistance butt or flash welding will produce welds 23a and 2417, as shown in Fig. 23.

Fig. 24 discloses a portion of a strip A6 mitre the inner frame corner with such upset diminishing towards the apex of the mitre cut, as indicated in Fig. 25.

Figs. 26 and 27, respectively, structures welded similarly to the tures shown in Figs. 18 and 19, but with the adjacent frame portions disposed in widely angled relationship, these twospecific examples being intended to illustrate that the herein disclosed method fully adapted to the forming of variously angled frame structures in which the mitre cuts will be of a degree suitable to produce the desired relative angulation of the adjacent frame sections.

In certain instances it may be desirable to use a strip A! which is formed as shown in Fig. 28, wherein the mitre show corner square or pointed outer corner, as shown in Figs. 29 to 31. When this corner structure is flash welded, the connected tie will be flashed or burned away and opposed edges will be forged together to form a weld similar to that illustrated in Fig. 6, w 'le if ordinary resistance butt 26, as shown in Fig. 30. Obviously, this deformed tie I49 may, if desirable, be subsequently trimmed off in order to smooth the surface of the frame. I

corner struc- From the foregoing it should be evident that the present invention provides a novel and improved method of forming mitred and welded frame structures from a single strip of material formed to provide bendable correlating means permitting angulation of adjacent frame portions or sections to welding relationship, with such correlating means so disposed as to permit the opposed meeting edges of the mitre cuts to be forged together under the pressure incident to electric resistance, welding,

While I have shown and described certain forms of mechanism and specific types of frame structures, it is to be understood that this has been done primarily for the purpose of presenting a clear disclosure, to those skilled in the art, of the essential features of the method involved and not to limit the scope of the invention as defined in the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. In a method of forming a metallic frame structure having a mitred and welded corner, the steps comprising mitre cutting a metal strip from which said structure is to be formed to define the location of said corner and provide opposed mitred edges relatively aligned for subsequent abutting engagement, said mitre out being formed to leave at the apex thereof only a bendable correlating tie connecting the adjacent parts of said strip and of sufficient strength to maintain said parts in correlated relationship, bending said strip at said tie to form a rounded corner and-to dispose the connected parts in relatively angled position and to bring said opposed edges into welding relationship, heating said parts to plasticisejsaid opposed edges and applying there'- to a translating pressure capable of abutting the plasticized edges with a force sufficient to forge said edges into a substantially homogeneous weld and simultaneously heating and swaging the metal defining said rounded corner and thereby tending to point said corner.

, 2. In a method of forming a metallic frame structure having amitred and welded corner, the steps comprising mitre cutting a metal strip from which said structure is to be formed to define the location of said corner and provide opposed mitred edges relatively aligned for subsequent abutting engagement, said mitre cut being-formed to leave only a bendable correlating tie connecting theadjacent parts of said strip and of sufficient strength to maintain said parts in correlated relationship, bending said strip at said mitre cut to form a rounded corner and to dispose the connected parts in relatively angled position and to bring said opposed edges into welding relationship, heating said parts to plasticise said tie and said opposed edges and applying thereto a translating pressure capable of upsetting said tie and 'of abutting the plasticised edges with a force sufficient to forge said edges into a substantially homogeneous weld and simultaneously heating and swaging the metal defining said rounded CO1"? ner and thereby tending to point said corner.

3. In a method of forming a metallic frame structure having a mitred and welded corner, the steps comprisingmitre cutting a metal strip from which said structure is to be formed to define the location of said corner and provide opposed mitred edges relatively aligned forsubsequent abutting engagement, said mitre out being formed to leave at the apex thereof only a bendable correlating tie connecting the adjacent parts of said strip and of sufficient strength to maintain said parts in correlated relationship, bending said strip at said tie to dispose the connected parts in relatively angled position and thereby form a rounded corner and to bring said opposed edges into welding relationship heating said parts to plasticize said tie and said opposed edges and applying thereto a translating pressure and thereby upsetting said tie outwardly in a manner tending to point said corner and abuttingthe plasticized edges with a force sufilcient to forge said edges into a substantially homogeneous weld.

4. In a method of forming a metallic frame structure having a mitred and welded corner,the steps comprising mitre cutting ametal strip from which said structureis to be formed to define the location of said corner and provide opposed mitred edges relatively aligned for subsequent abutting engagement, said mitre out being formed to leave only a bendable correlating tie connecting the adjacent parts of said strip, and of suflicient strength to maintain said parts in correlated re lationship, bending said strip at said mitre cut to, form a rounded corner and to dispose the connected parts in relatively angled position and to bring said opposed edges into Welding relationship, and subjecting the bent strip to an electric welding current of a magnitude sufiicient to plasticise said edges and applying thereto a translating pressure capable of abuttingthe plasticised edges with a force sufficient to forge said edges into a substantially homogeneous weld and simultaneously heating and swaging the metal defining said rounded corner and thereby tending to point said corner. I

5. In a method of forming a metallic frame structure having a mitred and Welded corner, the steps comprising mitre cutting a metal strip from which said structure is to be formed to define the location of said corner and provide opposed mitred edges relatively aligned for subsequent abutting engagement, and forming a welding projection extending from one of said edges and leaving only a bendable correlating tie connecting the adjacent parts of said strip and of sufficient strength to maintain said parts in correlated relationship, bending said strip at said mitre cut to dispose the connected 'parts in relatively angled position and to bring the edge of said welding projection into Welding relationship with a comparable portion of the opposed mitred edge, and subjecting the bent strip to an electric welding current of a magnitude sufficient to plasticise said edges and applying thereto a translating pressure capable of abutting the plasticised edges with a force sufiicient to forge said edges into a substantially homogeneous weld.

6. In a method of forming a metallic frame structure having a mitred and Welded corner, the steps comprising mitre cutting a metal strip from which said structure is to be formed to define the location of said corner and provide opposed mitred edges relatively aligned for subsequent abutting engagement, said mitre out being formed to leave only a bendable correlatingtie connecting the adjacent parts of said strip and of sufiicient strength to maintain said parts in correlated relationship, bending said strip at. said mitre cut to dispose the connected parts in relatively angled position and to bring said opposed edges into welding relationship, holding said correlated parts against accidental displacement, destroying said tie, and subsequently welding together said opposed edges.

7. In a method of forming a metallic frame structure having a mitred and welded corner, the 5 steps comprising mitre cutting a metal strip from which said structure is to be formed to define the location of said corner and provide opposed mitred edges relatively aligned for subsequent abutting engagement, said mitre cut being shaped to provide a welding projection extending from one of said edges and being formed to leave only a bendable correlating tie connecting the adjacent parts of said strip and of suflicient strength to maintain said parts in correlated relationship, bending said strip at said mitre cut to dispose the connected par-ts in relatively angled position and to bring the edge of said welding projection into welding relationship with a comparable portion of the opposed mitred edge, holdin said correlated parts against accidental displacement, destroying said tie, and subsequently welding together the opposed edges at said projection.

8. In a method of forming a metallic frame structure having a mitred and welded corner, the steps comprising mitre cutting a metal strip from which said structure is to be formed to define the location of said corner and provide opposed mitred edges relatively aligned for subsequent abutting engagement, said mitre out being shaped to provide a welding projection extending from one of said edges and being formed to leave only a bendable correlating tie connecting the adjacent parts of said strip and of suflicient strength to maintain said parts in correlated relationship, bending said strip at said mitre cut to dispose the lated parts against accidental displacement and subjecting them to an electric flash welding cur: rent of a magnitude suflicient to destroy said tie and to plasticise said contacting edges, and subsequently applying to said parts a translating pressure capable of abutting the plasticised edges with a force suflicient to forge said edges into a substantially homogeneous projection weld.

9. The method of forming metallic casement and Window frames from a continuous metal strip of the type having an outwardly extending co-planar flange and a connecting web, which comprises forming mitre cuts extending through said strip and into said co-planar flange corresponding to the positions of the corners of a frame, trimming the ends of said strip to provide rent, said mitre cuts when formed extending through the inner co-planar flange and web of said strip and partially into the other co-planar uncut portion in the latter flange of suflicient strength to retain the adjacent portions of the strip in cooperating relation when the strip is bent, said uncut portion in the latter flange also being of such cross-section that it will fuse upon subjection to said welding current and result in a substantially continuous weld throughout the entire cross-section of the frame at the mitred corners thereof.

10. The method of forming metallic frames and like structures having angularly disposed portions formed from a contiuuous strip, which comprises mitre cutting the strip from which the frame is to be formed at points corresponding to the corners of the frame, said mitre cuts extending from the inside of the strip to a depth sufficient to leave only a small uncut bendable portion in the strip at the apex of the'mit're cutsto retain the adjacent parts in welding relation when bent into their final position, and subsequently subjecting the joint formed between the angularly disposed meeting portions of the strip at said mitre cut to a butt welding current to fuse said uncut bendable portion and form a substantially homogeneous weld throughout the entire area of the meeting surfaces of the angularly disposed portions.

11. The method of forming metallic window and door frames from a continuous preformed strip having a folded irregular cross-section, which comprises cutting mitre cuts in said preformed strip with the apex thereof located at points corresponding to the outer corners of the finished frame, said mitre cuts extending through the folded portion of said preformed strip a distance sufficient to leave a small uncut portion at the corners of the frame of suflicient strength'to erating relation during and after the bending operation, and subsequently subjecting the bent strip at said mitre cuts to an electrical butt welding current of suflicient magnitude to simultaneously fuse the uncut portion of the strip at said mitre cuts and weld the meeting edges of the strip at the mitre cuts.

12. The method of forming metallic window and door frames from a continuous preformed having an outwardly extending flange,

points corresponding to the corners of the finished frame, said mitre cuts extending through the major portion of said strip and into the outwardly extending flange a distance sufficient to leave a small uncut portion in said flange of sufiicient strength to retain the adjacent portions of the strip in operating relation during and after the bending operation, bending said strip on said small uncut portion to bring the sides of the mitre cut in meeting relation, and subsequently subjecting the bent strip at said mitre cuts to an electric butt welding current to simultaneously fuse the uncut portion in said flange and weld the meet ing edges of the strip at the mitre cuts.

of forming metallic frames at points corresponding to the corners of the frame, the uncut portions in the parallel flanges of said formed strip being of sufiicient crossframe. 14. The method of forming metallic door and continuous strip having spaced parallel extending flanges and a connecting web that forms the inside surface of the frame, which comprises cutting mitre cuts in said strip at points corresponding to the corners of the frame, said mitre cuts when formed extendwindow frames from a ing through the connecting web of said strip and throughout the entire cross-section of the frame at the mitred corners thereof.

15. In a method of forming a metallic frame having mitred and welded corners, the steps comprising mitre cutting a metal strip from which said frame is to be formed at points corresponding to the corners of the frame to provide opposed mitred edges relatively aligned for subsequent abutting engagement, each of said mitre cuts being formed to leave only a bendable correlating tie connecting the adjacent parts of said strip and of sufficient strength to maintain said parts in correlated relationship, mitreing the terminal ends of said strip, bending said strip at the respective mitre cuts to form a rounded corner and to dispose the several parts in relatively angled positions to form said frame and bring said opposed edges and said mitred ends into welding relationship, heating the corner portions of said frame toplasticise the opposed edges thereof and applying thereto a translating pressure capable of abutting the plasticised edges with a force sufiicient to weld said edges together to complete the frame and simultaneously heating and swaging the metal defining each of said rounded corners and thereby tending to point said corners.

16. In a method of forming a metallic frame having mitred and welded corners, the steps comprising mitre cutting a metal strip from which said frame is to be formed at points corresponding to the corners of the frame to provide opposed mitred edges relativelyaligned for subsequent abutting engagement, each of said mitre cuts being formed to leave only a bendable correlating tie connecting the adjacent parts of said strip and of sufficient strength to maintain said parts in correlated relationship, mitreing the terminal ends of said strip, bending said strip at the respective mitre cuts to form a rounded corner and to dispose the several parts in relatively angled positions to form said frame and bring said opposed edges and said mitred ends into welding relationship, and subjecting the corner portions of said frame to an electric welding current of a magnitude sufficient to plasticise the opposed edges thereof and applying thereto a translating pressure capable of abutting the plasticised edges with a force suflicient to weld said edges together to complete the frame and simultaneously heating and swaging the metal defining each of said rounded corners and thereby tending to point said corners.

1'7. In a method of forming a metallic frame having mitred and welded corners, the steps comprising mitre cutting a metal strip from which said frame is to be formed at points corresponding to the corners of the frame to provide opposed mitred edges relatively aligned for subsequent abutting engagement, each of said mitre cuts being formed to leave only a bendable correlating tie connecting the adjacentv parts of said strip and of sufficient strength to maintain said parts in correlated relationship, mitreing the terminal ends of said strip, bending said strip at the respective mitre cuts to dispose the several parts in relatively angled positions to form said frame and bring said opposed edges and said mitred ends into Welding relationship, holding the angled parts against accidental displacement, destroying the several connecting ties, and subsequently welding together the opposed edges and ends to complete the frame.

ALBERT LANG. 

